1. Field of the Invention
This invention is directed to a staged combustion of fuel in a furnace to control the output of nitrous oxide in the exhaust stack gas, and to apply the heat of the exhaust gas for drying the fuel processed in a grinding mill.
2. Description of the Prior Art
Combustion systems for the disposal of solid fuel in furnaces to utilize the heat of combustion to the production of electrical energy are disclosed in Hood U.S. Pat. No. 3,670,669 of Jun. 20, 1972 or Rouse U.S. Pat. No. 4,750,437 of Jun. 14, 1988. In these disclosures there is no teaching of control over the generations of objectionable levels of nitrous oxide emissions. It is known that fossil fuels when improperly burned produce a high order of nitric oxide. The improper burning occurs when the air is too excessive and the flame temperature is high. The control over the emissions of nitrous oxide is the concern of the present apparatus.